Clean your pennies using some things in your home

Materials

• 20 dull and dirty pennies
• ¼ cup white vinegar
• 1 teaspoon salt
• A clear shallow bowl (not metal)
• Paper towels
• Spoon

How Do I Do It

1. Put the salt and vinegar into the bowl and stir until it dissolves.
2. Put the pennies into the bowl for about 5 minutes. Watch them when they first go in. What do you see?
3. Take half the pennies out and place them on a paper towel.
4. Take the second half out and rinse them off very well. Place them on a paper towel and mark it as being “rinsed”.
5. Wait about an hour and then check back on your two piles. What differences are there between the two? Record the differences and make some guesses about why they are different. The rinsed pennies will be bright and new looking.

Reason

When the vinegar and salt dissolve the copper oxide they make it easier for the copper atoms to join with the oxygen in the air and the chlorine in the salt. When the pennies are not rinsed it allows the chemical reaction to occur. This makes up a compound called malachite which is what coats the dark pennies.